The present invention relates to smoke filters that reduce the concentration of components in a smoke stream, including methods and smoking devices related thereto.
Increasingly, governmental regulations require higher filtration efficacies in removing harmful components from tobacco smoke, e.g., carbon monoxide and phenols. With present cellulose acetate, higher filtration efficacies can be achieved by doping the filter with increasing concentrations of particles like activated carbon. However, increasing particulate concentration changes draw characteristics for smokers.
One measure of draw characteristics is the encapsulated pressure drop. As used herein, the term “encapsulated pressure drop” or “EPD” refers to the static pressure difference between the two ends of a specimen when it is traversed by an air flow under steady conditions when the volumetric flow is 17.5 ml/sec at the output end and when the specimen is completely encapsulated in a measuring device so that no air can pass through the wrapping. EPD has been measured herein under the CORESTA (“Cooperation Centre for Scientific Research Relative to Tobacco”) Recommended Method No. 41, dated June 2007. Higher EPD values translate to the smoker having to draw on a smoking device with greater force.
Because increasing filter efficacy changes the EPD of the filters, the public, and consequently manufactures, have been slow to adopt most technologies. Therefore, despite continued research, there remains an interest in developing improved and more effective compositions that minimally effect draw characteristics while removing higher levels of certain constituents in mainstream tobacco smoke like carbon monoxide and phenols.